// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/strings/utf_string_conversions.h"

#include <stdint.h>

#include "base/strings/string_piece.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversion_utils.h"
#include "build/build_config.h"

namespace base {

namespace {

    // Generalized Unicode converter -----------------------------------------------

    // Converts the given source Unicode character type to the given destination
    // Unicode character type as a STL string. The given input buffer and size
    // determine the source, and the given output STL string will be replaced by
    // the result.
    template <typename SRC_CHAR, typename DEST_STRING>
    bool ConvertUnicode(const SRC_CHAR* src,
        size_t src_len,
        DEST_STRING* output)
    {
        // ICU requires 32-bit numbers.
        bool success = true;
        int32_t src_len32 = static_cast<int32_t>(src_len);
        for (int32_t i = 0; i < src_len32; i++) {
            uint32_t code_point;
            if (ReadUnicodeCharacter(src, src_len32, &i, &code_point)) {
                WriteUnicodeCharacter(code_point, output);
            } else {
                WriteUnicodeCharacter(0xFFFD, output);
                success = false;
            }
        }

        return success;
    }

} // namespace

// UTF-8 <-> Wide --------------------------------------------------------------

bool WideToUTF8(const wchar_t* src, size_t src_len, std::string* output)
{
    if (IsStringASCII(std::wstring(src, src_len))) {
        output->assign(src, src + src_len);
        return true;
    } else {
        PrepareForUTF8Output(src, src_len, output);
        return ConvertUnicode(src, src_len, output);
    }
}

std::string WideToUTF8(const std::wstring& wide)
{
    if (IsStringASCII(wide)) {
        return std::string(wide.data(), wide.data() + wide.length());
    }

    std::string ret;
    PrepareForUTF8Output(wide.data(), wide.length(), &ret);
    ConvertUnicode(wide.data(), wide.length(), &ret);
    return ret;
}

bool UTF8ToWide(const char* src, size_t src_len, std::wstring* output)
{
    if (IsStringASCII(StringPiece(src, src_len))) {
        output->assign(src, src + src_len);
        return true;
    } else {
        PrepareForUTF16Or32Output(src, src_len, output);
        return ConvertUnicode(src, src_len, output);
    }
}

std::wstring UTF8ToWide(StringPiece utf8)
{
    if (IsStringASCII(utf8)) {
        return std::wstring(utf8.begin(), utf8.end());
    }

    std::wstring ret;
    PrepareForUTF16Or32Output(utf8.data(), utf8.length(), &ret);
    ConvertUnicode(utf8.data(), utf8.length(), &ret);
    return ret;
}

// UTF-16 <-> Wide -------------------------------------------------------------

#if defined(WCHAR_T_IS_UTF16)

// When wide == UTF-16, then conversions are a NOP.
bool WideToUTF16(const wchar_t* src, size_t src_len, string16* output)
{
    output->assign(src, src_len);
    return true;
}

string16 WideToUTF16(const std::wstring& wide)
{
    return wide;
}

bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output)
{
    output->assign(src, src_len);
    return true;
}

std::wstring UTF16ToWide(const string16& utf16)
{
    return utf16;
}

#elif defined(WCHAR_T_IS_UTF32)

bool WideToUTF16(const wchar_t* src, size_t src_len, string16* output)
{
    output->clear();
    // Assume that normally we won't have any non-BMP characters so the counts
    // will be the same.
    output->reserve(src_len);
    return ConvertUnicode(src, src_len, output);
}

string16 WideToUTF16(const std::wstring& wide)
{
    string16 ret;
    WideToUTF16(wide.data(), wide.length(), &ret);
    return ret;
}

bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output)
{
    output->clear();
    // Assume that normally we won't have any non-BMP characters so the counts
    // will be the same.
    output->reserve(src_len);
    return ConvertUnicode(src, src_len, output);
}

std::wstring UTF16ToWide(const string16& utf16)
{
    std::wstring ret;
    UTF16ToWide(utf16.data(), utf16.length(), &ret);
    return ret;
}

#endif // defined(WCHAR_T_IS_UTF32)

// UTF16 <-> UTF8 --------------------------------------------------------------

#if defined(WCHAR_T_IS_UTF32)

bool UTF8ToUTF16(const char* src, size_t src_len, string16* output)
{
    if (IsStringASCII(StringPiece(src, src_len))) {
        output->assign(src, src + src_len);
        return true;
    } else {
        PrepareForUTF16Or32Output(src, src_len, output);
        return ConvertUnicode(src, src_len, output);
    }
}

string16 UTF8ToUTF16(StringPiece utf8)
{
    if (IsStringASCII(utf8)) {
        return string16(utf8.begin(), utf8.end());
    }

    string16 ret;
    PrepareForUTF16Or32Output(utf8.data(), utf8.length(), &ret);
    // Ignore the success flag of this call, it will do the best it can for
    // invalid input, which is what we want here.
    ConvertUnicode(utf8.data(), utf8.length(), &ret);
    return ret;
}

bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output)
{
    if (IsStringASCII(StringPiece16(src, src_len))) {
        output->assign(src, src + src_len);
        return true;
    } else {
        PrepareForUTF8Output(src, src_len, output);
        return ConvertUnicode(src, src_len, output);
    }
}

std::string UTF16ToUTF8(StringPiece16 utf16)
{
    if (IsStringASCII(utf16)) {
        return std::string(utf16.begin(), utf16.end());
    }

    std::string ret;
    // Ignore the success flag of this call, it will do the best it can for
    // invalid input, which is what we want here.
    UTF16ToUTF8(utf16.data(), utf16.length(), &ret);
    return ret;
}

#elif defined(WCHAR_T_IS_UTF16)
// Easy case since we can use the "wide" versions we already wrote above.

bool UTF8ToUTF16(const char* src, size_t src_len, string16* output)
{
    return UTF8ToWide(src, src_len, output);
}

string16 UTF8ToUTF16(StringPiece utf8)
{
    return UTF8ToWide(utf8);
}

bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output)
{
    return WideToUTF8(src, src_len, output);
}

std::string UTF16ToUTF8(StringPiece16 utf16)
{
    if (IsStringASCII(utf16))
        return std::string(utf16.data(), utf16.data() + utf16.length());

    std::string ret;
    PrepareForUTF8Output(utf16.data(), utf16.length(), &ret);
    ConvertUnicode(utf16.data(), utf16.length(), &ret);
    return ret;
}

#endif

string16 ASCIIToUTF16(StringPiece ascii)
{
    DCHECK(IsStringASCII(ascii)) << ascii;
    return string16(ascii.begin(), ascii.end());
}

std::string UTF16ToASCII(StringPiece16 utf16)
{
    DCHECK(IsStringASCII(utf16)) << UTF16ToUTF8(utf16);
    return std::string(utf16.begin(), utf16.end());
}

} // namespace base
